Problem: Divide. Write your answer in simplest form. $ \dfrac{4}{5} \div \left(-\dfrac{2}{9}\right) = {?} $
Explanation: Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $-\dfrac{2}{9}$ is $-\dfrac{9}{2}$. Therefore: $ \dfrac{4}{5} \div \left(-\dfrac{2}{9}\right) = \dfrac{4}{5} \times \left(-\dfrac{9}{2}\right) $ $ \phantom{\dfrac{4}{5} \div \left(-\dfrac{2}{9}\right)} = \dfrac{4 \times (-9)}{5 \times 2} $ $ \phantom{\dfrac{4}{5} \div \left(-\dfrac{2}{9}\right)} = -\dfrac{36}{10} $ Simplify: $ -\dfrac{18}{5}$